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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1857 (Engine Controls And Fuel - 3.5L (L66) - DTC P0030 To DTC P0222) >> DTC P0030, P0036, P0050, or P0056 >> Test Description

Test Description

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 4:  If all DTCs are set for either the front sensors or the rear sensors, the ignition voltage circuit to the heaters may be open. The front sensors and rear sensors share the same fuse.
Heated Oxygen Sensor (HO2S) Open Circuit

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Powertrain Control Module Connector End Views  or  Engine Controls Connector End Views 
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Start the engine.
  2. Allow the engine to idle for at least 30 seconds.
  3. Observe the DTC information with a scan tool.
Does DTC P0030, DTC P0036, DTC P0050, or DTC P0056 set?		 - Go to Step 4  Go to Step 3 
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 4  Go to Diagnostic Aids In This Test
4  Are DTCs P0030, P0036, P0050, and P0056 set at the same time? - Go to Step 12  Go to Step 5 
5
  1. Turn OFF the ignition.
    2. IMPORTANT: The ignition must be OFF when disconnecting or connecting the heated oxygen sensor (HO2S) electrical connector.
  2. Disconnect the appropriate HO2S.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the ignition voltage circuit of the HO2S and the powertrain control module (PCM) housing.
Does the test lamp illuminate?		 - Go to Step 6  Go to Step 12 
6 Connect a test lamp between the ignition voltage circuit of the HO2S and the heater control circuit.
Does the test lamp illuminate?		 - Go to Step 8  Go to Step 7 
7
  1. Connect a test lamp between the ignition voltage circuit of the HO2S and the heater control circuit.
  2. With a scan tool command the HO2S heater ON and OFF.
 Does the test lamp flash ON and OFF?		 - Go to Step 10  Go to Step 9 
8
  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Test the heater control circuit between the HO2S and the PCM for a short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 11 
9
  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Test the heater control circuit between the HO2S and the PCM for an open, a short to voltage or high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 11 
10 Test for an intermittent and for a poor connection at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 13 
11 Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 14 
12
    IMPORTANT: The ignition voltage circuit supplies voltage to other components. Make sure you test all circuits for a short to ground or test all components for being shorted that share the ignition voltage circuit.
  1. Repair the open or the grounded ignition voltage circuit of the HO2S. Refer to Wiring Repairs .
  2. Replace the fuse if necessary.
Did you complete the repair?		 - Go to Step 15  -
13 Replace the HO2S. Refer to the appropriate procedure:
Did you complete the replacement?		 - Go to Step 15  -
14
  1. Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
  2. Perform the idle learn procedure. Refer to Idle Learn .
Did you complete the replacement?		 - Go to Step 15  -
15
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 2  Go to Step 16 
16 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle System OK
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